Multifilament products made from resorbable polymers, such as copolymers of glycolide and lactide, and monofilament products made from resorbable polymers, such as polydioxanone (PDO), are well known in the prior art, and widely used in wound closure and general surgery. However, these products undergo rapid loss of strength retention in vivo, which limits their application primarily to fast healing repairs, and repairs where prolonged strength retention is not necessary. For example, while a surgeon may use a resorbable multifilament suture to approximate soft tissue that is not under significant tension, a surgeon will generally not use a resorbable suture when loads on the suture can be very high and remain high for a prolonged period, such as in rotator cuff repairs. Instead, surgeons will typically use permanent sutures for rotator cuff repairs even though it would be desirable to use a suture that is completely resorbed once healing is complete. Similarly, a surgeon may use a resorbable monofilament suture or mesh to approximate soft tissue that is not under significant tension, but will generally not use a resorbable monofilament suture or mesh when loads on the device can be very high and remain high for a prolonged period, such as in hernia repair. Instead, surgeons will typically use permanent (polypropylene) meshes for hernia repairs even though it would be desirable to use devices that completely resorb after healing is complete.
Thus in the practice of surgery there currently exists a need for a resorbable multifilament yarn with a high tenacity and prolonged strength retention, and a resorbable monofilament fiber with high tensile strength and prolonged strength retention. These multifilament yarns and monofilament fibers would allow the surgeon to use resorbable devices instead of permanent devices when high strength is initially required, or when prolonged strength retention is necessary. For example, the multifilament yarn could be used to make multifilament sutures suitable for the repair of rotator cuffs and other ligaments and tendons, or multifilament mesh suitable for hernia repair or breast lift procedures. And the monofilament fiber could be used to make monofilament sutures suitable for face-lift procedures, or monofilament meshes suitable for hernia repair, breast reconstruction and mastopexy.
Resorbable multifilament yarns and monofilament fibers have previously been prepared from poly-4-hydroxybutyrate (P4HB). P4HB (TephaFLEX® biomaterial) is a strong, pliable thermoplastic polyester that, despite its biosynthetic route, has a relatively simple structure. Upon implantation, P4HB hydrolyzes to its monomer, and the monomer is metabolized via the Krebs cycle to carbon dioxide and water.
U.S. Pat. No. 8,287,909 to Martin et al. discloses medical devices containing melt-blown nonwovens of poly-4-hydroxybutyrate and copolymers thereof with average fiber diameters of 1 μm to 50 μm. WO 2011/159784 to Cahil et al. discloses medical devices containing dry spun nonwovens of P4HB and copolymers thereof, and continuous processing methods for their preparation.
Odermatt et al. MonoMax Suture: A new long-term absorbable monofilament suture made from poly-4-hydroxybutyrate, Int. J. Polymer Science, Article 216137, 12 pages (2012) disclose a monofilament suture made from P4HB, but does not disclose multifilament yarn or multifilament sutures made from P4HB. U.S. Pat. Nos. 7,641,825 and 8,084,125 to Rizk disclose non-curling sutures of P4HB that are made by relaxing and annealing P4HB monofilament. Rizk does not disclose P4HB multifilament yarn or sutures with high tenacity or prolonged strength retention. In both Odermatt and Rizk, improvement of handling properties is achieved by relaxing the P4HB monofilament suture fiber resulting in a fiber that is not highly oriented.
Williams, et al. Poly-4-hydroxybutyrate (P4HB): a new generation of resorbable medical devices for tissue repair and regeneration, Biomed Tech. 58(5):439-452 (2013) discloses monofilament and multifilament fibers of P4HB.
U.S. Pat. Nos. 8,034,270 and 8,758,657 to Martin et al. disclose monofilament and multifilament knitted meshes of P4HB produced by knitting monofilament and multifilament fibers of P4HB. P4HB multifilament with tenacity ranging from 3.1 to 4.1 grams per denier, denier per filament ranging from 10.3 to 33.8, and elongation to break from 58 to 114% is disclosed.
U.S. Pat. No. 8,747,468 to Martin discloses P4HB monofilament and multifilament fiber, coatings and spin finishes for these fibers, and medical devices made from P4HB monofilament and multifilament fibers. The P4HB multifilament fibers have tenacities ranging from 6.524 to 8.081 grams per denier, and denier per filament ranging from 1.98 to 2.27.
U.S. Pat. No. 8,016,883 to Coleman et al. discloses methods and devices for rotator cuff repair, including medical devices containing knitted meshes of P4HB and nonwovens made from P4HB multifilament fibers. A P4HB multifilament fiber with a tenacity of 6.04 grams per denier, and denier per filament of 4.4 is disclosed.
WO 2015/006596 to Rizk et al. discloses soft suture anchors and preparation of P4HB monofilament and P4HB multifilament.
US Patent Application No. 2010/0057123 to D'Agostino and Rizk, and US Patent Application No. 2009/0112259 to D'Agostino disclose recombinant expressed bioabsorbable polyhydroxyalkanoate monofilament and multifilament self-retaining sutures.
There is still a need for multifilament fibers with improved strength retention and a high tenacity, and monofilament fibers with improved tensile strength.
It is an object of the present invention to provide a resorbable multifilament yarn with high tenacity, and a resorbable monofilament fiber with high tensile strength.
It is another object of the present invention to provide a resorbable multifilament yarn and a resorbable monofilament fiber with prolonged strength retention.
It is still a further object of the present invention to provide a resorbable multifilament yarn with high knot strength, pliability, and a good drape, and a resorbable monofilament fiber with good knot strength and pliability.
It is yet another object of this invention to provide methods to produce resorbable multifilament yarn with high tenacity or prolonged strength retention, and resorbable monofilament fiber with improved productivity and with high strength or prolonged strength retention.
It is still another object of this invention to provide methods to prepare medical devices and implants from the resorbable multifilament yarns and monofilament fibers.
It is still yet another object of this invention to provide methods to implant devices made from resorbable multifilament yarns and monofilament fibers that have high tenacity and prolonged strength retention.